Semi-automatic or automatic stirrup machines or bending machines which work by continuous feeding are already known in the prior art. Bending and stirrup machines which bend bars, wire or the like in any shape by bending either clockwise or counterclockwise have also been developed.
It has been particularly noticed that a wellknown type of stirrup machine utilizes a bending method based on a bending unit with a fixed fork around which a bending pin is made to partially rotate clockwise or counterclockwise making it re-enter and pass either above or under the bending bar. The expulsion of the finished product is caused by a central pin which is coaxial to the rotation axis of said bending pin.
In other cases, this pin acts not only as an expeller, but also as shearing element. These first types of machines are at a very advanced basis, but they are very complicated and expensive because they require a large number of moveable parts. In other cases, said central pin is eliminated and the fork is movable axially effacing in order to allow the expulsion of the finished product in connection with a shearing unit (U.S. Pat. Nos. 3,991,600, issued Nov. 16, 1976, and 4,049,026, issued Sept. 20, 1977.